Digital radio broadcasting technology delivers digital audio and data services to mobile, portable, and fixed receivers. One type of digital radio broadcasting, referred to as in-band on-channel (IBOC) digital audio broadcasting (DAB), uses terrestrial transmitters in the existing Medium Frequency (MF) and Very High Frequency (VHF) radio bands. HD Radio™ Technology, developed by iBiquity Digital Corporation, is one example of an IBOC implementation for digital radio broadcasting and reception.
IBOC DAB signals can be transmitted in a hybrid format including an analog modulated carrier in combination with a plurality of digitally modulated carriers or in an all-digital format wherein the analog modulated carrier is not used. Using the hybrid mode, broadcasters may continue to transmit analog AM and FM simultaneously with higher-quality and more robust digital signals, allowing themselves and their listeners to convert from analog-to-digital radio while maintaining their current frequency allocations.
One feature of digital transmission systems is the inherent ability to simultaneously transmit both digitized audio and data. Thus the technology also allows for wireless data services from AM and FM radio stations. The broadcast signals can include metadata, such as the artist, song title, or station call letters. Special messages about events, traffic, and weather can also be included. For example, traffic information, weather forecasts, news, and sports scores can all be scrolled across a radio receiver's display while the user listens to a radio station.
IBOC DAB technology can provide digital quality audio, superior to existing analog broadcasting formats. Because each IBOC DAB signal is transmitted within the spectral mask of an existing AM or FM channel allocation, it requires no new spectral allocations. IBOC DAB promotes economy of spectrum while enabling broadcasters to supply digital quality audio to the present base of listeners.
Multicasting, the ability to deliver several programs or data streams over one channel in the AM or FM spectrum, enables stations to broadcast multiple streams of data on separate supplemental or sub-channels of the main frequency. For example, multiple streams of data can include alternative music formats, local traffic, weather, news, and sports. The supplemental channels can be accessed in the, same manner as the traditional station frequency using tuning or seeking functions. For example, if the analog modulated signal is centered at 94.1 MHz, the same broadcast in IBOC DAB can include supplemental channels 94.1-1, 94.1-2, and 94.1-3. Highly specialized programming on supplemental channels can be delivered to tightly targeted audiences, creating more opportunities for advertisers to integrate their brand with program content. As used herein, multicasting includes the transmission of one or more programs in a single digital radio broadcasting channel or on a single digital radio broadcasting signal. Multicast content can include a main program service (MPS), supplemental program services (SPS), program service data (PSD), and/or other broadcast data.
The National Radio Systems Committee, a standard-setting organization sponsored by the National Association of Broadcasters and the Consumer Electronics Association, adopted an IBOC standard, designated NRSC-5B, NRSC-5B, the disclosure of which is incorporated herein by reference, sets forth the requirements for broadcasting digital audio and ancillary data over AM and FM broadcast channels. The standard and its reference documents contain detailed explanations of the RF/transmission subsystem and the transport and service multiplex subsystems. Copies of the standard can be obtained from the NRSC at http://www.nrscstandards.org. iBiquity's HD Radio™ Technology is an implementation of the NRSC-5B IBOC standard. Further information regarding HD Radio Technology can be found at www.hdradio.com and www.ibiquity.com.
Other types of digital radio broadcasting systems include satellite systems such as XM Radio, Sirius and WorldSpace, and terrestrial systems such as Digital Radio Mondiale (DRM), Eureka 147 (branded as DAB), DAB Version 2, and FMeXtra. As used herein, the phrase “digital radio broadcasting” encompasses digital audio broadcasting including in-band on-channel broadcasting, as well as other digital terrestrial broadcasting and satellite broadcasting.
Various approaches have been proposed for purchasing an item of interest by entering a command at a radio broadcast receiver based on digital data and content received with the receiver. For example, U.S. Pat. No. 6,925,489 describes an approach in which identification information is extracted from a current broadcast of a piece of music or other type of information of interest to a user using a digital audio broadcast receiver in response to a user command and stored in a memory or other storage device. The extracted information is then later delivered over a network connection to a server which permits the user to purchase the corresponding item U.S. Pat. No. 6,957,041 describes an approach in which a listener can respond to items in a radio broadcast such as music, advertisements, fund raising drives, or interactive listener polls during the broadcast, wherein data such as song title and artist, author or publisher, and IP address for the location of the digital content is transmitted using the RBDS/RDS data stream. Purchase requests can then be transmitted via wireless transmission or by accessing the Internet using a personal computer or wireless phone. U.S. Pat. No. 7,010,263 describes an approach in which a satellite radio receiver accepts user input identifying interest in music or data being played and/or displayed such that an ID signal is stored on removable media identifying the selection being played and/or displayed. The user can then download or place an order for the desired selection from a web site.
The present inventors have observed that in some applications ambiguities may arise in tagging content of interest in digital radio broadcast systems because program service data identifying an item of interest may not be entirely aligned temporally with the audio content heard by the user. The present inventors have identified a need for enhancing the temporal alignment at the receiver of program service data and the audio content (e.g., songs, advertising, etc.) to which the program service data corresponds to reduce ambiguities in identifying content of interest tagged by a user and to improve the user experience in tagging content of interest.